Abstract:Pulsed signals in Earth station receiver spectrum bands have traditionally occurred due to unwanted emissions from adjacent-band transmitters such as radars and altimeters. Analog Earth station receivers sometimes experience interference from such emissions. The trend toward increasing use of digital receivers, coupled with a possible future increase in pulsed signals, have raised the question of the circumstances under which pulsed emissions may cause interference to such receivers. This report documents the results of measurements in which a variety of co-channel pulsed signals were injected into the radio frequency (RF) front-end of an operational, television receive-only (TVRO) digital Earth station. The results identified the susceptibility of the Earth station to pulsed interference as a function of pulse characteristics that included pulse width, pulse repetition rate (both constant and jittered), and peak amplitude. The results indicate that digital Earth station receivers may be vulnerable to interference that creates either a contiguous block of symbol errors or a long series of symbol errors. Interference with lower pulse repetition rates, pulse widths, and duty cycles may also produce effects; in those cases results show the interference amplitude may be increased by as much as 50 dB above the carrier level before significant interference occurs. Quantitative interference thresholds are provided for the performance of electromagnetic compatibility analyses between pulsed interference sources and digital Earth station receivers. Examples of such analyses are provided.

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